Spot welding is a process in which contacting metal surfaces are joined by the heat obtained from resistance to electric current flow. Work-pieces are held together under pressure exerted by opposing electrodes. The spot welding process uses two shaped electrodes, formed from a copper alloy, to concentrate an electrical welding current into a small “spot” and to simultaneously clamp the metal surfaces together. Forcing a large electrical welding current through the spot will melt the metal and form the weld. Spot welding can deliver a lot of electrical welding current to the spot in very short time periods (approximately 250 milliseconds). The short timeframe permits the welding to occur without excessive heating to the remaining portions of the work-pieces.
In some instances, the joined work-pieces are made of steel or steel alloys. In other instances, the joined work-pieces can be made of other metals, such as for example, aluminum or aluminum alloys. The properties of the material forming the joined work-pieces can be critical factors in determining the amount of electrical welding current required to complete the spot weld. In some instances, such as when the work-pieces are made from aluminum, the aluminum material has a high thermal and electrical conductivity. In these instances, the amount of electrical welding current required to complete the spot weld can be several times the amount of electrical welding current required to complete the spot weld for materials having a lower thermal and electrical conductivity.
The high amounts of electrical welding current can cause distortion of an electrode tip. In addition, brittle deposits can form on portions of the electrode tip. After a period of use, the electrode tips typically are either replaced or returned to an original profile, with any existing deposits removed. The process of restoring the electrode tip to a renewed and useable condition is referred to as “dressing” the electrode. It would be advantageous if the electrode tips could be dressed more easily.